<u>Answer:</u> The correct answer is the mass number of the most common isotope of the element is 24.
<u>Explanation:</u>
We are given:
An element having atomic number 12 is magnesium and atomic mass of the element is 24.305
The image corresponding will be 
The number '24.305' is the average atomic mass of magnesium element.
Average atomic mass is defined as the sum of masses of each isotope each multiplied by their natural fractional abundance.
Formula used to calculate average atomic mass follows:

Average atomic mass of magnesium = 24.305 amu
As, the average atomic mass of magnesium lies closer to the mass of Mg-24 isotope. This means that the relative abundance of this isotope is the highest of all the other isotopes.
The 'Mg-24' isotope is the most common isotope of the given element.
Hence, the correct answer is the mass number of the most common isotope of the element is 24.
 
        
             
        
        
        
There's a lot of capillaries in the lungs because the blood needs to be transferred and the capillaries are the smallest vessels that can do this.
        
             
        
        
        
Answer:
AWWWWWWWWWWWWWWWW SOOO NICEEE
 
        
             
        
        
        
Answer:
Double bond
Explanation:
an alkene is a unsaturated hydrocarbon which means that it contain at least one double bond
 
        
                    
             
        
        
        
Answer:
i think C the higher the frequency the lower the energy of light.